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LOG ENTRY - 20-JUL-2011 Matt Borland
Flight: 8 - 20-JUL-2011 - 1.4 hr - S-Turns, Touch-and-goes
Depart: KCOS ~1020 Arrive: KCOS ~1144
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It has been a while since my last entry. Since my last entry, I encountered
some communication issues inflight with my instructor in flight #6, but we
talked about it and now things are getting along much better. We had been
doing several ground-tracking maneuvers, and small issues like identifying a
shared point of reference were causing confusion while in the cockpit.
In the meantime I have also become very accustomed to talking with ATC. It is
now pretty straightforward. They are there to help you, and I realize now that
for better or worse, they mess up more often than I do. This is not a slight
against ATC, it's just a demanding job and there are going to be minor mistakes
from time to time by both ATC and pilots.
It has been warm lately, and though this doesn't pose a direct threat to our
flights, it's a major consideration when planning flights in general. As air
heats up, it becomes less dense and thus less capable of providing lift. As a
result very hot temperatures can cause an aircraft to perform as though it is
flying at a much higher alititude. Each aircraft has an operating ceiling and
even below that ceiling performance degrades significantly. What hotter
temperatures do is effectively lower that ceiling. A plane that has a ceiling
of 17,000 feet under normal conditions may only have a ceiling of 12,000 feet.
As a result, you need to perform a density altitude calculation to ensure that
your plane can operate at the altitudes you plan to fly. This is a particular
concern when you start at a high elevation. Colorado Springs Municipal is at
approximately 6,175 feet above sea level, and some mountain airports are above
9,000 feet.
My instructor is now trusting me to taxi along the tightly-fit planes in the
aero club ramp, which is a good sign that my taxi skills are increasing. I
remember veering significantly the first few times; now keeping the plane
pretty well centered to the yellow line is becoming second-nature. I am also
getting better at not hitting the brakes unless I want to; I can better control
my feet's working of the pedals.
At Colorado Springs Municipal (KCOS) there are three runways: 17L/35R, 13/31,
and 17R/35L. Runways are numbered by the magnetic heading that they provide
to a moving aircraft. So if you land at 17L, you are landing at approximately
170 degrees (south-ish) based on magnetic north. Note that this is different
from true north; this sometimes causes runway designations to change as magnetic
north shifts over time. The L/R designation is for the relative position of
the runway to other similarly aligned runways. Since a runway can be entered
from either side, description of the runway in general will indicate two
directions (e.g. 17R/35L) that are separated by 180 degrees. However when
landing or taking off, you are given only one direction (e.g. 17R). The
direction is largely based off of the wind. You want to take off into the wind
in order to provide the maximum amount of lift. Having a tailwind would 'take
wind out of your sails' basically speaking and decrease lift significantly.
A crosswind can affect your movement in various ways, but in general you want
to minimize crosswind. As a result, most runways are aligned to provide a
headwind based on prevailing wind patterns. Many larger airports have
perpendicular runways to allow for more options if there are heavy crosswinds
on primary runways.
Runway 13/31 at KCOS has been under construction the whole time I have been
flying. It is an example of a runway whose names have changed due to the
magnetic shift; it used to be 12/30. This runway runs parallel to the military
flight line and is primarily used for smaller aircraft. 13/31 is 8,269 feet
long whereas 17R/35L is 11,022 feet and 17L/35R is 13,501 feet. Since 13/31
is now open, it is usually the preferred option for small craft using the
military flight line.
We taxied to 31 (so, taking off into the northwest) via taxiway Bravo 5, which
places us on the runway with less than half the runway remaining. For a small
plane like the T-41C, this is not a problem, because even with the heat and the
short runway, not much is needed to take off. We performed a short-field
takeoff, which is exactly what it sounds like: taking off using a minimum of
runway. This involved setting the flaps to 10 degrees, then holding the brakes
while throttling the plane up all the way. Once the max RPM is reached, then
you release the brakes and let the plane zoom down the runway. My instructor
estimated we took off in less than 900 feet of runway. This meant that even
by starting with less than half the runway in front of us (probably less than
4,000 feet), we used less than a quarter of what was remaining to take off.
Once aloft I followed ATC to guide us out of the airport region and to the
practice area. There we performed a clearing maneuver and practiced a wind-
drift circle, steep turns, and S-Turns. I am still having trouble keeping
my altitude even, and also judging the angle of bank needed to successfully
make an even S-Turn. Other problems I noticed are that in keeping my hand
on the throttle (which you need to do) I inadvertently pull it back a little,
causing the power to drop a little. Also, I'm not using the trim enough to
decrease the amount by which I pull/push on the yoke. By not doing so, I
strain the muscles in my arm and they pulse as they get tired. A day later,
I'm sore in my forearm because I was pulling too hard on the yoke.
Then we went back to the airport to perform touch-and-goes. To do so, you
announce to approach your intention to perform touch-and-goes, and to remain
'in the pattern.' As you move around the airport, you are placed along a
pattern in relation to the runway you are approaching. The patterns follow
a rectangular shape including the runway as one of its sides. Patterns are
designated as either right or left, indicating the kind of turn that the plane
takes around the pattern (i.e. 'left' would be counter-clockwise and 'right'
would be clockwise). Landing involves many aspects of flying coming together
at once. You want to be approaching at a reasonable angle to the runway, and
obviously you want to be aligned to the runway. However, among most other
aspects, your airspeed is probably the most important single aspect. You need
to maintain good coordinated flight and the appropriate airspeed for the
aircraft and point along your approach. It is very fun to come in for a
landing! You want to align your plane with the runway and head for the
'numbers' on the near side of the runway. In the T-41C, you are generally
around 80 mph on your final leg. You can achieve this primarily through
balancing power and flaps. Flaps are used to extend the chord line (length
of wing from leading to trailing edge) and increase its angle. When performing
a standard landing, you use about 20 degrees of flaps. Above 20 degrees can
be used if you want additional drag; at 40 degrees it is akin to using
airbrakes. You can feel the effect immediately. As you cross the numbers,
just about as you hit the ground-effect of air, you flare the plane which helps
burn off additional speed and allows you to position the plane correctly to
let the plane stall and settle gently on the runway. You don't want to land
the plane before a stall because you don't want the plane to become airborne
again unexpectedly.
In the case of a touch-and-go, you simply put the throttle full in and adjust
the flaps as necessary, and perform a takeoff. Depending on what ATC has
proscribed, you follow the pattern. In this case, we touched 35R, then after
gaining about 300 feet, turned left and proceeded to the midpoint between the
two 17/35 runways, then ran perpendicular to the runways, maintaining a climb to
7,000 feet (about 800 feet above ground level). Then we turned right into our
base leg, then to final leg for 35L. We touched that, then followed a right
pattern back through the center of the airport, and touched down at 35L again.
Our day was about done, so on this go around we called ATC to let them know
we were going in for a full stop, so they directed us to land on 13. We flew
over my office on the pattern for 13, and my instructor flew us in for the
stop.
We took the plane to the fuel pit to refuel, and afterwards we had to wait to
taxi as a couple of C-130s roared slowly by before we could head back to the
aero club ramp.
The plan next time is to just practice touch-and-goes, which should be a lot of
fun. Hopefully I will have more to report on next week!